1. Field of the Invention
The present invention relates to a thin film electroluminescent panel which can be used for a display device in a personal computer, a word processor or the like.
2. Prior Art
A thin film electroluminescent (hereinafter referred to as EL) panel has an EL element formed on a glass substrate. The EL element should be protected from humidity in order to maintain its reliability.
In a prior art EL panel, an EL element formed on a glass substrate was covered by a backup glass, and the space between the EL element and the backup glass was filled with silicone oil containing silica gel powder and black insulator powder. The silicone oil was sealed hermetically.
In another prior art thin film EL panel, a laminate film was used to prevent the penetration of humidity into the EL element (for example, JP-A 61-290693).
However, in the described prior art thin film EL panel, the cost of silicone oil with silica gel powder and black insulator powder was high. Further, many steps and a long time were needed for manufacturing a thin film EL panel. For example, the space between the EL element and the backup glass had to be evacuated upon filling the silicone oil. Therefore, it was very difficult to lower the cost of the thin film EL panel. Further, the thickness and the weight of the backup glass itself set limits on making the thickness of the thin film EL panel thinner and making the weight of the panel lighter.
On the other hand, the latter prior art thin film panel did not take into account the moisture absorption function specifically in order to secure high reliability. Further, it did not intend to improve the contrast thereof.